In a related art, the OpenFlow protocol, proposed in 2008 by the Stanford University, is a protocol which separates the control from the forwarding. An external control plane entity uses the OpenFlow protocol to control a forwarding plane device to realize various forwarding logics, and the forwarding plane device mainly performs a controlled forwarding according to a flow table sent by an OpenFlow controller. The OpenFlow protocol further evolves to become a Software Defined Network (SDN) technology, i.e., various complex network applications can be achieved under a control plane using software programming, for example, an Evolved Packet System (EPS)/General Packet Radio Service (GPRS) network can be achieved using the SDN, wherein the EPS network is a fourth generation mobile communication network defined by the 3rd Generation Partnership Project (3GPP), and the GPRS network is the third generation mobile communication network defined by the 3GPP.
An architecture realizing the EPS/GPRS network using the SDN is as shown in FIG. 1. In FIG. 1, UE is a communication terminal; an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) is a wireless access network part, wherein the E-UTRAN is composed of evolved NodeBs (eNodeBs). The core network part is a software-defined Evolved Packet Core (EPC, i.e., the core network part of the EPS) network, all the Unified Gateways (UGW) are universal gateway devices, and the roles thereof are controlled by a control signalling of an SDN Controller (Controller or controller). As shown in FIG. 1, a UGW where a Serving Gateway (SGW) or a Serving GPRS Support Node (SGSN) is located functions as the SGW or the SGSN according to an indication of the controller, a UGW where a Packet Data Network Gateway (PGW) or a Gateway GPRS Support Node (GGSN) is located functions as the PGW or the GGSN according to an indication of the Controller, and similarly, another UGW functions as a non-3GPP access gateway or an Evolved Packet Data Gateway (ePDG). It is not precluded that two, three or more network element roles fall on one UGW, if they fall on one UGW, the interfaces among the network elements become internal interfaces. In fact, the SGW, the PGW, the GGSN, the SGSN, the ePDG, the non-3GPP access gateway and the like which are controlled by indications of the controller all perform user plane functions of corresponding mobile network gateways in the existing GRPS system and EPC system, while the control plane functions thereof are all integrated in the Controller. The Controller is responsible for the selection of a gateway (PGW/UGW, SGW/UGW, SGSN/UGW, GGSN/UGW) during a user access, and the Controller needs to consider constraint conditions such as subscription information and position information of the UE when selecting a UGW. For example, if the subscription of the UE allows a service to be distributed in the neighbourhood, the Controller selects for the UE a UGW which is close to the access point of the UE in terms of topology or address location to serve as the SGW/PGW/SGSN/GGSN, etc. In addition, the Controller is also responsible for the address management function of a subscribed user, including user address distribution, recycling, application for agency, external announcement, etc. The Controller allocates an address for the UE, designates a UGW which manages the address, and announces the UGW which is responsible for the address to an external router, and in this way, downlink data can be accurately routed to an appropriate UGW. Second, the Controller has a communication interface with the data centre, for example, a Deep packet inspection (DPI) and other functional modules, to enable the information interaction through an Xy interface, wherein the Xy interface is pronoun which only indicates that there is an interface used for the information feedback, while the name of the interface, a protocol adopted by the interface and a manner for the interface to feedback information are not determined.
According to the protocol defined by the present 3GPP standard organization for the EPS system and the GPRS system, the data communicates with the external PDN network or Internet through the PGW. However, such a routing method faces a problem that in the present network, the position of the PGW is relatively high, for some service data such as an internet service, the serious data circuitry and the waste of bandwidth resources will be caused by the fact that a large number of service data packets are routed to the PGW at a very high position. For such a problem, 3GPP also proposes some solutions, for example: 1, the position of the PGW in the network architecture is lowered (i.e., deploying the PGW in a distribution manner); or 2, the SGW/PGW which is close to the access point of the UE is selected when the UE accesses the network; or 3, a local gateway is deployed on a base station; or 4, a distribution gateway at a position close to the base station is selected to perform distribution via address translation, etc. The above distribution solutions can also be achieved in the EPS/GPRS network based on the SDN under the control of the Controller. However, the above solutions have the following defects: Solutions 1-3 are distribution based on PDN connection, that is to say, the UE establishes a PDN connection which corresponds to one IP address, all the services using the IP address/PDN connection must be entirely distributed or not distributed at all, but it cannot be achieved that the data flows of one part of applications using the IP address are distributed, while the data flows of the other part of applications using the IP address are not distributed. This is a defect for a terminal which only supports one IP address. For a terminal which supports multiple IP addresses, the simultaneous operation of applications under distribution and those not under distribution can be supported only when the multiple IP addresses are used, which is also a waste for the use of IP addresses. Solution 4 uses the network address translation (NAT) technology to distribute the service of a GPRS system based on the granularity of bearers, however, the technology is only suitable for the GPRS system but is not suitable for an EPS system, as an additional encryption technique is performed on the control signalling of the EPS. Furthermore, although solution 4 has finer-granularity distribution than solutions 1-3, the data distribution under the granularity of applications still cannot be achieved.
The distribution technology having the above-mentioned detects is disadvantageous not only for the user experience but also for the improvement of the competition of operators. Therefore, an application/service data flow granularity based data flow distribution technology is in urgent need at present.